MESSUI is an integrated front-end of MESS, which itself emulates hundreds of computers and consoles. MESSUI is similar in appearance to MAMEUI. Each emulation instance is accompanied by a windows-style menubar which is not normally part of MESS. This menubar is known as 'NEWUI'.

The current stable release is 0.159 (2015-02-25). Bleeding-edge releases are available every few days.